1. Field of the Invention
The present invention relates to dust collectors for vacuum cleaners and, more particularly, to a cyclone dust collector for such vacuum cleaners having a simple construction and effectively removing solids, including microparticles, from dust-laden air.
2. Description of the Prior Art
As well known to those skilled in the art, conventional vacuum cleaners are designed to suck dust-laden air under pressure from a target surface using strong suction force generated from a suction motor set within the cleaner body, and to filter the dust-laden air to remove dust, small or powdered solids from the air prior to discharging the filtered air from the cleaner body to the atmosphere.
In the prior art, paper filter bags have been used in such vacuum cleaners for filtering dust-laden air. However, the conventional paper filter bags are problematic in that such a filter bag has to be changed with a new one after a lapse of predetermined time, thus being inconvenient to users. Another problem of the conventional paper filter bags resides in that the filter bags reduce the suction force of the vacuum cleaners due to dust contained in the filter bags. In such a case, the cleaning effect of the vacuum cleaner is reduced.
In an effort to overcome the above problems experienced in the conventional paper filter bags, cyclone dust collectors designed to be almost semi-permanently used without being changed with a new one have been proposed.
Such cyclone dust collectors are conventionally classified into several types. The representative example of the conventional cyclone dust collectors is a dual-type cyclone dust collector, which comprises first and second collecting units connected to each other to form a desired cyclone collector.
In such a dual-type cyclone dust collector, the first collecting unit is used for removing relatively heavier or large-sized solids from dust-laden air, while the second collecting unit is used for removing relatively lighter or small-sized solids from the air.
Such conventional dual-type cyclone dust collectors are advantageous in that they don""t require separate paper filter bags, and are improved in their dust collecting effect in comparison with conventional single-type cyclone dust collectors since the dual-type collectors remove dust from dust-laden air twice through first and second cyclone dust collecting processes.
FIG. 1 shows the construction and operation of a conventional dual-type cyclone dust collector. As shown in the drawing, the conventional dual-type cyclone dust collector comprises first and second collecting units 1 and 2, which are connected to each other to form a desired cyclone collector. Of the two collecting units, the first unit 1 is used for removing relatively heavier or large-sized solids from dust-laden air, while the second unit 2 is used for removing relatively lighter or small-sized solids from the air discharged from the first unit 1.
The first collecting unit 1 has an external casing 1a, which forms the external housing of the dual-type cyclone dust collector and acts as a dust collection tub of the first unit 1. A first air guide port 1b is mounted to the upper portion of the external casing 1a, and is used for guiding dust-laden air into the external casing 1a. The first collecting unit 1 also has an air discharging tub 1c, which is concentrically set within the external casing 1a and is provided with a plurality of air discharging holes for allowing primarily processed air from the interior of the external casing 1a into the air discharging tub 1c. 
That is, the external casing 1a of the first collecting unit 1 forms the external housing of the dual-type cyclone dust collector, and primarily processes dust-laden air to remove relatively heavier or large-sized solids from the dust-laden air. In the first collecting unit 1, the removed solids are collected in the lower portion of the external casing 1a. The first air guide port 1b guides dust-laden air under pressure from a target surface into the external casing 1a using a suction force formed by a suction unit, comprising a suction fan 3 and a suction motor 4. The air discharging tub 1c is a cylindrical tub, which is concentrically set within the external casing 1a and is provided with air discharging holes for allowing the primarily processed air from the interior of the external casing 1a into the air discharging tub 1c. The primarily processed air, discharged into the air discharging tub 1c through the air discharging holes of the tub 1c, is introduced into the second collecting unit 2 so as to be secondarily and finally processed by said second collecting unit 2 as will be described later herein.
The second collecting unit 2 has an internal casing 2a, which is concentrically set within the air discharging tub 1c of the first collecting unit 1 at the central portion of said tub 1c. A second air guide port 2b is mounted to the upper portion of the internal casing 2a, and is used for guiding the primarily processed air from the interior of the air discharging tub 1c into the internal casing 2a. The second collecting unit 2 also has an air exhaust port 2c, which is used for discharging the finally processed air from the internal casing 2a into the atmosphere. A dust collecting chamber 2d is provided within the second collecting unit 2 at a position under the internal casing 2a. In the embodiment of FIG. 1, the dust collecting chamber 2d is defined within the bottom of the external casing 1a while communicating with the lower open end of the internal casing 2a and being separated from the first collecting unit 1 by a partition wall 2e. 
That is, the internal casing 2a of the second collecting unit 2 forms the body of said second collecting unit 2, and receives the primarily processed air from the air discharging tub 1c of the first collecting unit 1 through the second air guide port 2b. The above internal casing 2a has a conical hopper shape, with the diameter of the casing 2a being gradually reduced in a direction from the upper end to the lower open end. The interior of the internal casing 2a communicates with the dust collecting chamber 2d through its lower open end.
An air exhaust pipe 3a extends from the air exhaust port 2c of the second collecting unit 2, with the suction unit comprising the suction fan 3 and the suction motor 4 mounted to the outside end of the air exhaust pipe 3a, thus forming an air suction force for the first and second collecting units 1 and 2. In an operation of the dual-type cyclone dust collector, the suction unit generates a suction force for the dust collector. Due to such a suction force, dust-laden air is forcibly sucked from a target surface into the dust collector through the first air guide port 1b while being pressurized, and is primarily and secondarily processed by the first and second collecting units 1 and 2 prior to being discharged to the atmosphere through the air exhaust port 2c. 
The operational effect of such a conventional dual-type cyclone dust collector will be described in detail herein below. When the suction fan 3 is rotated by the suction motor 4, a desired suction force or suction pressure is formed within the dust collector. Therefore, dust-laden air under pressure is sucked from a target surface into the external casing 1a through the first air guide port 1b. 
After the dust-laden air is introduced into the external casing 1a through the first air guide port 1b, the air under pressure swirls within the external casing 1a at a high speed. In such a case, some relatively heavier solids are removed from the dust-laden air due to gravity, and are collected on the lower portion of the external casing 1a. The operational theory of such a cyclone dust collector is well known to those skilled in the art, and further explanation is thus not deemed necessary.
The primary cyclone dust collecting process, performed by the first collecting unit 1, cannot remove relatively lighter solids and microparticles from the dust-laden air swirling within the external casing 1a, but allows the relatively lighter solids and microparticles to flow into the air discharging tub 1c along with air so as to be introduced into the internal casing 2a of the second collecting unit 2 through the second air guide port 1b. 
In the second collecting unit 2, the air laden with relatively lighter solids and microparticles swirl within the internal casing 2a. During such a swirling action of the dust-laden air within the internal casing 2a, the solids and microparticles are separated from each other due to a difference in centrifugal force between them as follows.
That is, when the dust-laden air swirls within the internal casing 2a, the weighty solids are centrifugally forced to swirl down along the interior surface of the sidewall of the internal casing 2a to be finally dropped into the dust collecting chamber 2d. Meanwhile, the microparticles, having an almost negligible weight, are not centrifugally forced toward the sidewall of the internal casing 2a, but flows at the central portion within the internal casing 2a. 
Therefore, the second collecting unit 2 cannot remove such microparticles from air, but allows the microparticles to be discharged to the atmosphere together with processed air through the air exhaust port 2c, even though the unit 2 somewhat effectively removes weighty solids from air by making the solids centrifugally swirl down along the interior surface of the sidewall of the internal casing 2a to be finally dropped into and collected within the dust collecting chamber 2d. 
Such a conventional dual-type cyclone dust collector is thus problematic in that its second collecting unit 2 cannot remove such microparticles from air, but undesirably discharges the microparticles to the atmosphere together with processed air through the air exhaust port. This means that the conventional dual-type cyclone dust collector cannot accomplish a desired cleaning effect even though it is necessary for vacuum cleaners to almost completely remove solids, including such microparticles, from air. In the operation of the conventional dual-type cyclone dust collector, the microparticles pass through the suction fan 3 and the suction motor 4 prior to being discharged to the atmosphere, and so the microparticles are deposited on the fan 3 and the motor 4.
Another problem of the conventional dual-type cyclone dust collector resides in that the collector has a complex construction due to the two cyclone collecting units, and so it is very difficult to disassemble or assemble the parts of the collector when it is desired to remove collected dust and solids from the collector or to wash the parts of the collector.
Due to the complex construction of the conventional dual-type cyclone dust collector, the number of parts of the collector is increased. This finally increases the production cost and complicates the production process of the dust collector. Such a complex construction of the conventional dual-type cyclone dust collector also requires the size and volume of the collector to be enlarged, and so it is almost impossible to accomplish the recent trend of compactness of the dust collectors or compactness of vacuum cleaners.
In the conventional dual-type cyclone dust collector, the dust collecting chamber 2d of the second collecting unit 2 is set within the external casing 1a of the first collecting unit 1, and so the size of the dust collecting chamber 2d is undesirably limited. This finally limits the dust collecting capacity of the chamber 2d, and so it is necessary for a user to undesirably often remove collected dust and solids from the chamber 2d, thus being inconvenient to the user. Such a problem caused by the dust collecting chamber 2d having a small size may be overcome by enlarging the size of the external casing of the dual-type cyclone dust collector. However, such an enlargement in the size of the dual-type cyclone dust collector is not preferable since the enlarged size of the collector also necessitates an enlargement in the size of vacuum cleaners. This finally fails to accomplish the recent trend of compactness, lightness and smallness of such vacuum cleaners.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a cyclone dust collector for vacuum cleaners, which effectively removes solids, including microparticles, from dust-laden air.
Another object of the present invention is to provide a cyclone dust collector for vacuum cleaners, which has a simple construction, thus accomplishing the recent trend of compactness of the vacuum cleaners.
A further object of the present invention is to provide a cyclone dust collector for vacuum cleaners, which has a compact construction and an enlarged dust collecting capacity, thus being convenient to users.
In order to accomplish the above object, the present invention provides a cyclone dust collector for vacuum cleaners, comprising: an openable cyclone dust collection casing; an air inlet port formed on the sidewall of the casing such that the air inlet port introduces dust-laden air under pressure into the casing while forming a cyclone of the air within the casing; an air exhaust port provided at the top end of the casing for discharging the air from the casing to the atmosphere; a dust collecting filter provided within the casing for filtering the air before the air is discharged from the casing to the atmosphere through the air exhaust port; and a partition plate horizontally installed within the casing at a lower portion to define a dust collecting chamber within the casing at a position under the partition plate, the partition plate being provided with an opening for allowing solids and particles, removed from the air, to pass through the partition plate to reach the dust collecting chamber.
In the cyclone dust collector of this invention, the cyclone dust collection casing comprises: a lower body being open at its top; and a lid covering the open top of the lower body. In addition, the air inlet port is preferably formed at the upper portion of the sidewall of the casing, while the air exhaust port is preferably formed at the central portion of the lid.
In the cyclone dust collector, the dust collecting filter is detachably mounted to the lower surface of the lid at a central position such that it is possible to remove the dust collecting filter from the lid when necessary to wash or change the filter.
The opening of the partition plate is preferably defined by a cutout formed along the outside edge of the partition plate.
In addition, it is preferable to rotatably mount the partition plate to the sidewall of the casing. In an embodiment, the partition plate comprises two semicircular plate parts. In such a case, the two semicircular plate parts are commonly hinged to diametrically opposite positions of the casing at opposite ends of their linear edges, with two stoppers interiorly mounted to the sidewall of the casing so as to support lower surfaces of arcuate edges of the two plate parts. The two plate parts are thus rotatable only upward from the stoppers.
In the cyclone dust collector, the dust collecting filter preferably has a predetermined strength capable of enduring the pressure of the air passing through the filter. In an embodiment, the dust collecting filter has a cylindrical shape, and is corrugated on its surface to have an enlarged air contact surface. The dust collecting filter is preferably and longitudinally corrugated around its circumference. In addition, it is preferable to make the dust collecting filter using polyester. Such a polyester filter can be washed and reused several times.
The present invention also provides a vacuum cleaner, comprising: a body having both an air suction port for receiving dust-laden air under pressure and an air exhaust port for discharging the air from the body to the atmosphere after filtering the air; a suction unit provided within the body at a front portion and generating a suction force for sucking the dust-laden air into the body; and a cyclone dust collector used for removing solids, particles and other impurities from the dust-laden air through a cyclone dust collecting process and a filtering process, the cyclone dust collector being detachably installed within the body at a rear portion.
In the above vacuum cleaner, a cord reel is preferably provided within the body at a position under the cyclone dust collector. This cord reel receives an electric cord of the vacuum cleaner therein when the cord is fully retracted.